STUDY OBJECTIVE: In the context of calls to develop better systems for out-of-hospital clinical research, we seek to understand paramedics' perceptions of involvement in research and the barriers and facilitators to that involvement. METHODS: This was a qualitative study using semistructured focus groups with 58 United Kingdom paramedics and interviews with 30 US firefighter-paramedics. The study focused on out-of-hospital research (trials of out-of-hospital treatment for stroke), whereby paramedics identified potential study subjects or obtained consent and administered study treatment in the field. Data were analyzed with a thematic and discourse approach. RESULTS: Three key themes emerged as significant facilitators and barriers to paramedic involvement in research: patient benefit, professional identity and responsibility, and time. Paramedics showed willingness and capacity to engage in research but also some reticence because of the perceived sacrifice of autonomy and challenge to their identity. Paramedics work in a time-sensitive environment and were concerned that research would increase time taken in the field. CONCLUSION: Awareness of these perspectives will help with development of out-of-hospital research protocols and potentially facilitate greater participation.